Figure 5.

Effect of ER stress agents on steady-state mRNA levels of IPP isomerase in HepG2 cells. Equivalent amounts of total RNA (10 μg/lane) isolated from HepG2 cells cultured for 4 hours in the absence (control) or presence of 5 mM homocysteine, 2.5 mM DTT, 5 mM β-mercaptoethanol, 10 μM of the Ca²⁺ ionophore A23187, or 10 μg/ml tunicamycin were examined by Northern blot analysis using a radiolabeled IPP isomerase cDNA probe. Control for equivalent RNA loading was assessed using a radiolabeled GAPDH cDNA probe.